Phototropic Multiresponsive Active Nanogels.

Authors :: Otsuka I
Zhang X
Winnik FM
Source :: Macromolecular rapid communications [Macromol Rapid Commun] 2019 Dec; Vol. 40 (24), pp. e1900479. Date of Electronic Publication: 2019 Nov 10.
Publication Year :: 2019
Abstract: Aqueous dispersions of nanogels that respond to switches in environmental pH and/or temperature by changes in their hydrodynamic radius (R <subscript>h</subscript> ) and/or ζ-potential are prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization-induced thermal (70 °C) self-assembly (PITSA) of N-isopropylacrylamide (NIPAM) in the presence of a poly(methacrylic acid) (PMAA)-substituted macromolecular chain transfer agent and a cross-linker. Photochromic spiropyran (SP) moieties are coupled to the carboxylic acid groups of the nanogels. Upon UV irradiation, the neutral SP isomerizes to the zwitterionic merocyanine (ME) form. Upon UV light irradiation, microgels formed by assembly of SP nanogels undergo a collective motion toward the UV-light source.<br /> (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)